Answer:
55°
Explanation:
You want to know the additional angle a plane must turn through to be going south after it took off going east, then turned right 35°.
Bearing
The initial bearing angle was 90° (straight east). After turning right 35°, the airplane now has a heading of (90+35)° = 125°. To be going south (180°), the bearing must increase by ...
180° -125° = 55°
The airplane will have to turn 55° more to be heading due south.